What is Acid Rain?

written by: Summer Banks•edited by: Niki Fears•updated: 9/22/2009

Are you afraid to walk outside in the rain for fear of being burned by acid rain? Acid rain was once a real fear, today people are less likely to worry about the rain and its effects, but that lack of worry may be leading to the destruction of forests, lake animals and river animals.

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What is Acid Rain?

Acid rain is rainwater that falls from clouds in the form of a very weak acid. Both sulphuric and nitric acid are found in acid rain when collected and tested.

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How Does Rain Turn Acidic?

Pollution is the number one cause of acid rain. When air, water and soil is polluted, these pollutants eventually make their way into the cloud water and, thus the rain water.

Air pollution is the most common cause of acid rain. The pollutants that rise out of the smoke stacks of factories and the exhaust pipes of vehicles all contribute to acid rain. The pollutants rise into the atmosphere where they collect on the clouds and mix with the collecting moisture. When the rain falls, that rain is acid rain.

Water pollution and soil pollution work hand in hand in creating acid rain. As soils are polluted with chemicals from power stations and factories, the water runoff collects in rivers and ponds and eventually evaporates into the clouds only to be carried to another location and dropped as acid rain.

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Is Acid Rain Really Acid?

In all reality, the pH levels of acid rain can vary greatly. The pH levels will range from 0 (the most acidic) to 14 (the least acidic). All rainwater measuring in the area of 7 is considered "normal" or neutral.

Most acid rain falls in the pH range of 4 to 5. However, there have been some cases where acid rain has measured a pH of 2 to 3. Lemon Juice and Vinegar both fall into the acid category with this same pH.

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What Does Acid Rain Do to the Environment?

While vinegar and lemon juice certainly are not harmful to humans, the effects of this acidic pH level on forests, lakes and rivers is great.

When acid rain falls, it is absorbed by the soil and collected by lakes and rivers. The change in the pH of soil can alter the growth of plants and even render some plants unable to grow. When plants die, animals have less to eat and will either move on to another location or simply cease to exist.

In lakes and rivers, the collection of a lower pH and more acidic waters will kill fish and leave the waters inhabitable by water breathing species. Lakes and rivers most affected by acid rain will appear crystal clear but will house less fish populations than waters of more alkaline levels.

The fish eggs or roe are the most effected by acid rain. Fish eggs tend to hatch less often or not at all when gestating in acid waters.

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What Can Be Done About Acid Rain?

The answer to acid rain is pollution control. The less acidic gases emitted into the skies, the less acid rain will fall back to the Earth. Once thought of as a local or regional problem, today acid rain may be created in one country and travel thousands of miles before falling back to the Earth. Every country needs to look closely at air, soil and water pollution guidelines in order to stop acid rain.